Author Topic: Atkinson engine and CVT  (Read 15258 times)

ColinS

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Re: Atkinson engine and CVT
« Reply #45 on: August 19, 2018, 09:44:25 PM »
It works for me and I never use the speed limiter. Having looked at the manual, it only mentions depressing the accelerator fully, it does not mention going beyond the resistance of the detent.
I'm not sure what you mean "It works for me".  And surely "depressing the accelerator fully" means just that.

Skyrider

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Re: Atkinson engine and CVT
« Reply #46 on: August 19, 2018, 09:55:31 PM »
It works for me and I never use the speed limiter. Having looked at the manual, it only mentions depressing the accelerator fully, it does not mention going beyond the resistance of the detent.
I'm not sure what you mean "It works for me".  And surely "depressing the accelerator fully" means just that.

It works for me means it gives me more power after the increased resistance although I don't use the limiters. I still think it is an economy stop which many drivers will never discover as they will think they are at full throttle when they reach the resistance.
« Last Edit: August 19, 2018, 09:58:17 PM by Skyrider »

andruec

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Re: Atkinson engine and CVT
« Reply #47 on: August 19, 2018, 09:59:12 PM »
It works for me and I never use the speed limiter. Having looked at the manual, it only mentions depressing the accelerator fully, it does not mention going beyond the resistance of the detent.
I'm not sure what you mean "It works for me".  And surely "depressing the accelerator fully" means just that.

It works for me means it gives me more power after the increased resistance although I don't use the limiters. I still think it is an economy stop which many drivers will never discover as they will think they are at full throttle when they reach the resistance.
It's certainly possible. A pity there's no mention of it in the Jazz manual.

I just did a Google search for it and this time it found quite a few hits (I thought last time I tried it didn't find anything):

https://www.google.co.uk/search?q=accelerator+pedal+notch+at+bottom+of+travel&rlz=1C1CHBF_en-GBGB782GB782&oq=accelerator+pedal+notch+at+bottom+of+travel&aqs=chrome..69i57.5272j0j7&sourceid=chrome&ie=UTF-8

Lots of opinions, no-one seems to know for sure :-/

Maybe we could ask Honda. On the other hand why bother? I know what they will respond with:

"There is a notch at the bottom of the pedal and pressing past this point will make the car go faster."
« Last Edit: August 19, 2018, 10:04:34 PM by andruec »

ColinS

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Re: Atkinson engine and CVT
« Reply #48 on: August 19, 2018, 10:03:02 PM »
It works for me and I never use the speed limiter. Having looked at the manual, it only mentions depressing the accelerator fully, it does not mention going beyond the resistance of the detent.
I'm not sure what you mean "It works for me".  And surely "depressing the accelerator fully" means just that.

It works for me means it gives me more power after the increased resistance although I don't use the limiters. I still think it is an economy stop which many drivers will never discover as they will think they are at full throttle when they reach the resistance.
OK I see what you mean.  Just out of interest try the speed limiter some time (the manual one will do) and you will see what I am describing.  I think you may find that with the limiter set it wont try to change down until you go past the indent.  I don't have a CVT at my disposal so can't confirm that myself but I would be interested in your findings.

Skyrider

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Re: Atkinson engine and CVT
« Reply #49 on: August 19, 2018, 10:08:31 PM »
Maybe not realising that full power is beyond the resistance accounts for some of the incredible mpg figures claimed.  ;D

Just seen your post re try the limiter, I will have a go tomorrow, if I can figure out how it works, I am a cruise control user.

Downsizer

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Re: Atkinson engine and CVT
« Reply #50 on: August 20, 2018, 09:15:03 AM »
In my experience, pushing the accelerator beyond the normal stop point results in further gear reduction, raising the revs to c.5000, i.e. approaching peak power.  The beauty of he cvt for me is that it will give you whatever power you need regardless of road speed.
[/quote]

The reason it seems to give a gear ratio reduction is it allows the engine to produce full power. The CVT will have dropped to its lowest appropriate ratio long before the accelerator passed the detent in pedal travel.
[/quote]
No, there is definitely a further gearing reduction.  There has to be for the engine revs to rise to near full power at any given roagd speed.
« Last Edit: August 20, 2018, 09:19:32 AM by Downsizer »

Skyrider

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Re: Atkinson engine and CVT
« Reply #51 on: August 20, 2018, 09:26:12 AM »
@andurec. I owned a Focus 2.0 TDCI and a Ceed 1.6 diesel, both were manual transmissions and both had the resistance at the bottom of the accelerator travel. With both these cars there was info in the user manuals. In the Ford it it gave a turbo overboost for a short period, in the KIA it was an economy stop which released full power. I have driven many automatic cars which have had a transmission kickdown switch. The reason I think it is an economy device in the Jazz is my manual had it as does my CVT. The CVT does not need a kickdown switch, it works its magic long before you get to the resistance in the pedal. I had not considered the speed limiter angle but I will try it today if conditions are suitable, flooring a 1.5 rapidly puts you into licence threatening speeds! When I owned my previous manual cars with this device there was much forum discussion about it purpose.

Skyrider

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Re: Atkinson engine and CVT
« Reply #52 on: August 20, 2018, 09:36:19 AM »
I am not sure that the CVT needs to reduce its ratio for the engine to increase its revs when the power outputs we are talking about are in use. For example (these are off the top of my head figures) say the engine is producing 110bhp at the resistance, passing the resistance in the pedal almost instantly releases another 20bhp, the engine revs will increase rapidly without a gear change.

Jocko

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Re: Atkinson engine and CVT
« Reply #53 on: August 20, 2018, 10:00:56 AM »
IMHO the indent is to fool the driver into thinking the throttle is all the way down. To put it in the manual would kind of negate its purpose. In an emergency the driver will push his foot hard down anyway and easily overcome the resistance.
On a slightly different vein, my brother sold me his Carlton (his first automatic), after four years ownership, and didn't find out it had Kickdown until the week before he parted with it! In his case it was not reading the manual rather than in not being in there.

ColinS

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Re: Atkinson engine and CVT
« Reply #54 on: August 20, 2018, 10:12:30 AM »
IMHO the indent is to fool the driver into thinking the throttle is all the way down. To put it in the manual would kind of negate its purpose.
We know why it is present on the manual version (speed limiter override), it says so in the user manual and I have one so can confirm that.  It indubitable performs the same function in the CVT and I can also confirm that because I have driven an HR-V CVT. Skyrider may also confirm that for the Jazz later.

So the only question to be answered is that if it also performs a kick down function in the CVT.

Downsizer

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Re: Atkinson engine and CVT
« Reply #55 on: August 20, 2018, 10:17:40 AM »
I am not sure that the CVT needs to reduce its ratio for the engine to increase its revs when the power outputs we are talking about are in use. For example (these are off the top of my head figures) say the engine is producing 110bhp at the resistance, passing the resistance in the pedal almost instantly releases another 20bhp, the engine revs will increase rapidly without a gear change.
I don't see how the engine can deliver maximum power without increasing the revs to peak power level - the power curve dictates the maximum power at any given engine speed.

andruec

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Re: Atkinson engine and CVT
« Reply #56 on: August 20, 2018, 10:50:30 AM »
IMHO the indent is to fool the driver into thinking the throttle is all the way down. To put it in the manual would kind of negate its purpose.
We know why it is present on the manual version (speed limiter override), it says so in the user manual and I have one so can confirm that.  It indubitable performs the same function in the CVT and I can also confirm that because I have driven an HR-V CVT. Skyrider may also confirm that for the Jazz later.

So the only question to be answered is that if it also performs a kick down function in the CVT.
I experimented with it a bit last night. I don't think it performs a kick-down because the car can be kicked down without pushing the pedal that far. For instance I often kick-down to get the car out of Atkinson mode. However going past that notch does seem to get some extra power even after you've kicked down so I think Skyrider is probably correct. It's some kind of WOT (Wide Open Throttle) guard to prevent you accidentally demanding total power from the engine. Although if so I'm not entirely sure what the point is. It's also something that wasn't felt necessary on the CVT-7 or the Mk2 both of which I have owned :-/

ColinS

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Re: Atkinson engine and CVT
« Reply #57 on: August 20, 2018, 11:52:06 AM »
IMHO the indent is to fool the driver into thinking the throttle is all the way down. To put it in the manual would kind of negate its purpose.
We know why it is present on the manual version (speed limiter override), it says so in the user manual and I have one so can confirm that.  It indubitable performs the same function in the CVT and I can also confirm that because I have driven an HR-V CVT. Skyrider may also confirm that for the Jazz later.

So the only question to be answered is that if it also performs a kick down function in the CVT.
I experimented with it a bit last night. I don't think it performs a kick-down because the car can be kicked down without pushing the pedal that far. For instance I often kick-down to get the car out of Atkinson mode. However going past that notch does seem to get some extra power even after you've kicked down so I think Skyrider is probably correct. It's some kind of WOT (Wide Open Throttle) guard to prevent you accidentally demanding total power from the engine. Although if so I'm not entirely sure what the point is. It's also something that wasn't felt necessary on the CVT-7 or the Mk2 both of which I have owned :-/
Ok I think that answers our question.  It is just there for speed limiter override.

And I think you are both correct @andruec, @skyrider.  What would be the point in adopting that on a CVT.  The acronym speaks for itself.

Skyrider

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Re: Atkinson engine and CVT
« Reply #58 on: August 20, 2018, 01:25:09 PM »
I have done some experiments in my 1.5 CVT this morning. Bearing in mind this is the first and last time I will use the speed limiter, as I consider it a device of the devil. I expect a car to respond to control inputs not sit with its brain in neutral!

At varying speeds from 45 to 65 mph with the limiter on I slowly pressed the accelerator, the limiter did not cut out until way past the accelerator resistance and was almost fully depressed. Pressing the accelerator more rapidly had a similar effect. My conclusion is it is not a limiter cut out.

With the limiter off I pressed the accelerator through the resistance at varying rates and car speeds. The CVT changed down before I got to the resistance. After the resistance there was an increase in engine noise and revs but I am not sure if the CVT reduced its ratio any more as by this time the car was taking off like a scared cat.

This is all a bit academic because the treatment I gave my car this morning was not normal driving, and you would rarely need to go beyond the resistance in normal driving in a 1.5 unless you were trying a risky overtake.

My conclusion is still it is an economy stop.
« Last Edit: August 20, 2018, 01:31:43 PM by Skyrider »

Downsizer

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Re: Atkinson engine and CVT
« Reply #59 on: August 20, 2018, 01:55:18 PM »
I like the analogy - we should rename it "the scared cat switch"!

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